Encapsulates the notion of a mime type. Can be used at render time, for example, with:

class PostsController < ActionController::Base
  def show
    @post = Post.find(params[:id])

    respond_to do |format|
      format.html
      format.ics { render :text => post.to_ics, :mime_type => Mime::Type["text/calendar"]  }
      format.xml { render :xml => @people.to_xml }
    end
  end
end